1. Field of the Invention
The invention relates to an image guided surgery system comprising a position detection system.
2. Description of Related Art
Such an image guided surgery system is known from the U.S. Pat. No. 5,389,101.
Image guided surgery systems are generally employed to assist the surgeon to position a surgical instrument during an operation. During complicated surgery it is often very difficult or even impossible for the surgeon to see directly where in the interior of the patient he/she moves the surgical instrument. On a display device the image guided surgery system shows the surgeon the position of a surgical instrument relative to the region where the surgical operation is being performed. Thus, the image guided surgery system enables the surgeon to move the surgical instrument inside the patient and beyond direct sight, without risk of damaging vital parts.
The position detection system of the known image guided surgery system comprises two cameras which pick-up images of the surgical instrument from different directions. The image guided surgery system includes a data processor for deriving the position in space of the surgical instrument from image signals from both cameras. During the operation images that had been collected earlier are being shown to the surgeon. For example computed tomography (CT) image or magnetic resonance (MRI) images which were formed before the operation may be displayed on a monitor. The data processor calculates the corresponding position of the surgical instrument in the image. In the displayed image the actual position of the surgical instrument is shown together with an image of a region in which the surgical instrument is used.
Such an image guided surgery system is preferably employed in neuro-surgery to show the surgeon the position of the surgical instrument in the brain of a patient who is being operated on.
A drawback of the known image guided surgery system is that it is difficult to void that the surgical instrument is moved beyond the measuring field. Should the instrument be moved outside the measuring field, then the position detection system will no longer be able to detect the position of the surgical instrument.